Jigsaws are power tools which comprise a reciprocating saw blade for cutting a work piece of wood or other material. Most jigsaws comprise a plastic housing containing an electric motor. The rotary output of the motor is geared to a drive conversion mechanism which converts rotary motion of the motor output into reciprocating motion of an output shaft to cause reciprocating motion of a saw blade.
Jigsaws are usually designed to enable the blade to be removed from the output shaft. This serves two purposes. Firstly, due to the high frictional forces encountered when in use, jigsaw blades are subject to wear and tear and have limited lifetimes, so that there is a necessity to enable the blade to be easily replaced. Secondly, several different types of blade may be supplied with the jigsaw to enable it to be used to cut a variety of different types of workpiece, or cut the workpiece in a variety of ways.
European Patent Application EP0792713 describes a jigsaw blade clamp which comprises a channel formed in a jigsaw output shaft shaped to accommodate a jigsaw blade and a pin that is urged into contact with the blade by a spring, such that the pin forces the blade into the channel thereby holding it in place. This prior art clamp suffers from the drawback that if sufficient force is applied to the blade, it can still slip out of place and even be pulled away from the jigsaw.
Preferred embodiments of the present invention seek to overcome the above disadvantage of the prior art.